Add hide code and output options for dynamic notebooks

[JavierCladellas]

Add the possibility to write the following options in dynamic notebooks to handle cell appearance:

• hide_code: To hide all code from a notebook cell and only insert the results
• open: To automatically open the cell results, without having to click each time on the >results button.
• hide_output: To hide the output (results) of a cell.

The options can be specified, for example, as:

[%hide_code%raw%dynamic%open,python]
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... Some notebook cell ...
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